We assert that the principal role of an engineer is to make decisions associated with the design of an artifact. We define decision-based design as the process of partitioning, planning and making decisions to design and artifact that meets specified objectives. Decisionbased design is a new term coined to emphasize a different perspective from which to develop methods for design. In the context of decision-based design we propose to develop for use in unified lifecycle engineering design: a conceptual model for unifying the process associated with design, manufacturing and maintenance; the means to partition an artifcat model into subsystems and components, and the means to develop a strategy and implement a plan of action for obtaining knowledge about the artifact so that it can be manufactured.
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